Does anyone have a good explanation of Permissions?

Does anyone have a good explanation of permissions and all the different ways to set them and pass products from a vendor to a customer?

Ask a nice easy one!

Fair use says an item must be copiable OR transferable, so you can't set no permissions.
Modify you can toggle on and off.

If you set the perms on the OBJECT (be that one prim or a linked set) before it goes on sale, that will be the object perms it gets.

Things IN an object's inventory (that can include other items, scripts, no copy (to you) textures etc.) will stack upwards... so if your object is no copy, and a script no transfer, no mod the overall package is no copy, no mod, no transfer.

Staying with this one... if they rez the object it will show as "you can modify" in the edit window. They can resize, recolour etc.

Notecards that are no copy, no mod can't be read. Scripts that are either no copy OR no modify (or both) can't be read. Scripts that are no copy, modify can be reset by the user successfully (at least the last time I checked, with the current perms borks I'm not 100% sure of this).

Textures which are full perms (except for library textures) can be downloaded to your disk and played with (although copyright legislation may make this of dubious legality, but it is possible) and reuploaded. There are texture sellers that sell full perms textures with the expectation that you can modify their textures out of world for your own use. That, because it's licensed explicitly is certainly OK - reselling the tweaked textures is not.

I think that covers most of the bases. And although I can't guarantee it, I'm pretty sure it's right.

Almost right, as it will set the perms of the object to the perms of the script. Modify is a tricky one. If the script is no mod, you can still set the object to mod. Do that in your inventory, and it get's rid of the no mod tag on the object in the next persons inventory. Do it in world, and they will still get the no mod tag, but when they rez it it'll be mod. It's weird that way.